The present invention relates to a novel article, being a toothbrush, and in particular to a toothbrush having a flexible zone in its head.
When brushing one""s teeth, particularly with a conventional toothbrush having a rigid head, it can be difficult to reach all parts of the teeth in order to brush the teeth satisfactorily. It is also difficult with such brushes to maintain an optimum angle between the teeth and the head of the toothbrush for effective brushing and cleaning, necessitating continual repositioning of the brush in the hand throughout the brushing process. Consequently, there is a tendency to apply excess brushing pressure to some teeth and insufficient pressure to other teeth. The resultant combination of excess brushing pressure and inadequate cleaning or bad cleaning technique can result in damage to both teeth and gums.
Although angled-head toothbrushes have been suggested as an attempt to overcome some of these difficulties, they do not satisfactorily meet all the requirements.
Proposals have also been made for toothbrushes having flexible handles or flexible zones in their handles to assist in accommodating the orientation of the bristle-bearing head of the brush of the profile of an individual""s teeth and gums. Such toothbrushes are disclosed for example in EP-A-0336641, U.S. Pat. No. 4,520,526, DE-OL-3640898, DE-OL-3612108, CH-0155730 and IT-485723.
In some circumstances it is desirable to further improve the flexibility of the head relative to the direction of the handle of the toothbrush.
Accordingly the present invention provides a toothbrush, having a handle and at one end thereof a bristle-bearing head, wherein the head is in the form of two or more segments flexibly and resiliently linked to each other and/or to the handle, one or more of the segments being bristle-bearing.
The toothbrush head of this invention, being flexible, can flex under the action of toothbrushing so as to accommodate itself to the differing profiles of individual users"" teeth. In particular, teeth generally lie in a xe2x80x9cCxe2x80x9d shaped curve within the upper and lower jaw, the row of teeth consequently having a convex outer curve and a concave inner curve. The flexible head of the tooth-brush of the inventors can bend to accommodate itself to both the convex and concave curves of the teeth generally better than would be the case with a conventional rigid-headed toothbrush.
In a first embodiment of this invention, the head may be formed as an integral extension to the handle. In a second embodiment the handle may be extended into the form of a frame wholly or partly surrounding the head, and to which the head is linked, preferably flexibly and resiliently. Within such a frame the head may be integrally formed, or may be made as a separate part and fastened into the frame.
The head may be in a variety of segmented forms. For example in a first form, suitable both for when the head is formed as an integral extension of the handle or when the head is surrounded by a frame, the head may have bristles mounted in one face, and the opposite face may have one or more grooves therein. In such a head the lands between the grooves comprise the segments, and flexible resilient linking occurs about the thinned regions of head material at the bottom of the grooves.
In this first form of head, one or more of the grooves should be transverse to the longitudinal axis of the handle, to provide flexibility of the head in a plane containing this axis. Additionally or alternatively there may be one or more grooves aligned parallel to the longitudinal axis of the handle and/or one or more grooves aligned. Preferably there are only transverse grooves. Suitably there need be only one such transverse groove.
In this first form of head, the depth and/or width of the grooves, and/or the frequency of the grooves per unit distance, along the length and/or across the breadth of the head may be varied. By variation in this way the flexibility and/or resilience of linking and consequently of the whole head along the length and/or across the breadth of the head may be varied. For example by having deeper grooves at the end of the head furthest from the handle, the head can be made to be more flexible at this end. Preferably flexibility and/or resilience only along the length of the head is controlled in this way.
In this first, grooved, form of head, one or more of the grooves may be wholly or partly filled with an elastomeric material. In this way too the flexibility and/or resilience of the head may be varied and contamination of the grooves by for example toothpaste deposits etc may be reduced or avoided completely. The colour of the elastomeric material may be the same as that of the material of the head, or it may be different thereby achieving a distinctive stripped or otherwise patterned appearance.
When the head is of the above described grooved form, and is wholly or partly surrounded by a frame, the frame preferably completely surrounds the head. The head may be linked to the frame handle at various points around the perimeter of the head, but is preferably linked to the frame at one or more points in a plane that includes the longitudinal axis of the handle. The head may alternatively or additionally be linked at points in a plane at 90xc2x0 to the longitudinal axis of the handle. These links may be bridging portions of the material of the head or frame, and by varying the dimensions of these bridging portions the degree of flexibility and/or resilience of the linking may be varied. For example the degree of flexibility and/or resilience of these links can be made such that the head may be made to rock about these links, in addition to flexing.
In a second segmented form for example, suitable for use when the head is surrounded by a frame, the head is in the form of one or more chains of bristle carriers, flexibly and resiliently linked to each other, and linked at least one end of the chain to the frame. The linking may be by bridging portions of the material of the head or frame, and by varying the dimensions of the degree of flexibility and/or resilience of the linking may be varied.
In a third segmented form for example the head may be in the form of segments which are not joined to each other but are flexibly and resiliently linked to the handle or to the frame. In one such embodiment, the head may be in the form of segments linked to the handle or to the frame by thin spines, e.g., stalk-like bridging portions for example oriented inwordly from a surrounding frame. By varying the dimensions of these stalk-like bridging portions the degree of flexibility and/or resilience of the linking may be varied.
In all forms of the head in which a frame is present, the frame may bear bristles, which may have the same or different distribution, length, orientation, colour or stiffness to those on the head. Conveniently bristles when present on the frame may be shorter than those on the head.
The bristles may be uniformly distributed over the head, and the frame, if present, but preferably the bristles are distributed in discrete tufts. There may be one or more tufts per segment. In one embodiment of a head which is in the form of chains of linked bristle carriers, each carrier may carry one or two tufts of bristles.
In all forms of the toothbrush of this invention in Which there is a frame, the space(s) between the head and the frame may be partly or wholly filled with a flexible and/or resilient material, which may be an elastomeric material and/or may be in the form of a thin diaphragm. By varying the degree of such filling and the material used the degree of flexibility and/or resilience of the head may be varied.
The toothbrush (i.e. the handle, head and bristles) of the invention may be made of materials which are conventional in the manufacture of toothbrushes especially, plastics materials. Suitable plastics materials include, for example, polyamides and polypropylenes. An example of a suitable polyamide is the material xe2x80x98Ultramid B3xe2x80x99 (Trade mark, marketed by BASF, Federal Republic of Germany), having a modulus of elasticity (DIN 53452) of 3000. An example of a Suitable polypropylene is the material xe2x80x98Novolene 1100 HXxe2x80x99 (Trade mark, marketed by BASF, Federal Republic of Germany), which is a homopolymer and has a modulus of elasticity (DIN 53457) of 1400. Such a polypropylene homopolymer may optionally be used in admixture with a polypropylene block co-polymer, such as the material xe2x80x98Novolene 2500 HXxe2x80x99 (Trade mark, marketed by BASF, Federal Republic of Germany), for example in an 80:20 mixture by weight (1100 HX: 2500 HX).
The handle may be of a shape which is conventional in the manufacture of toothbrushes. It may however be advantageously made in the form described in EP-0336641-A, the contents of which are included by reference, more particularly as described in column 1 lines 36xe2x80x349 thereof.
In use, the toothbrush of this invention may be used for cleaning the teeth by an entirely conventional toothbrushing hand action, preferably in a manner recommended by dental health authorities. The toothbrush of the invention may also be used in electrically driven toothbrushes.